There has been conventionally known a technique of determining, with use of a magnet and a magnetic sensor, opening and closing of a foldable (openable and closable) electronic device such as an electronic dictionary, a personal computer, or a mobile phone.
Each of (a) and (b) of FIG. 12 illustrates a configuration of a magnet and a magnetic sensor in a conventional electronic device. As shown in FIG. 12, an electronic device 200 has (i) an upper casing 210, having a screen and a magnet 212, which is provided on a plus side of a Z axis and (ii) a lower casing 220, having a magnetic sensor 223, which is provided on a minus side of the Z axis. The upper casing 210 and the lower casing 220 are connected to each other, via a hinge 230.
According to the electronic device 200, in a case where the upper casing 210 and the lower casing 220 are folded (closed), the magnetic sensor 223 of the lower casing 220 detects magnetic fields generated by the magnet 212 of the upper casing 210 (see (a) of FIG. 12). In contrast, in a case where the upper casing 210 is rotated to open, the magnetic sensor 223 does not detect the magnetic fields generated by the magnet 212. This is because the magnetic sensor 223 moves away from the magnet 212 (see (b) of FIG. 12).
There has been recently developed an electronic device having an upper casing 210 that can be folded towards a back side of a lower casing 220. For example, Patent Literature 1 discloses a mobile phone in which an upper casing, having an image display section, can be folded towards both of a front side (dial key side) and a back side (a side opposite to the dial key side) of a lower casing having dial keys.
Patent Literature 1 further discloses a technique of determining (i) opening and closing of an electronic device and (ii) a state where the upper casing is folded towards a back surface of a lower casing. Such a technique is realized by a configuration in which (i) a magnetic sensor is provided at a position where magnetic fields are generated in a case where an image display section of the upper casing is folded towards a dial key side and (ii) another magnetic sensor is provided at a position where magnetic field are generated in a case where the image display section is folded towards a side opposite to the dial key side.